1. Field of the Invention
The invention relates to a method for preparation of high purity, crystalline cobalt nitrate from spent Co/SiO2 catalyst.
2. Description of the Related Art
Cobalt is a rare metal. Silica supported cobalt-based Co/SiO2 catalyst is highly active in catalytic hydrogenation. Recycling cobalt from a cobalt-based spent catalyst decreases environmental pollution and improves the utilization of the cobalt resources.
A typical method for recycling cobalt includes precipitating cobalt ions to yield Co(OH)2, and dissolving Co(OH)2 in nitric acid to obtain Co(NO3)2.6H2O. However, the purity of Co(NO3)2.6H2O obtained by this method is less than 98%. In addition, the fine granules of intermediate CoS produced during the recycling process are difficult to filter, which causes cobalt loss during filtration and leads to a low recovery rate of cobalt.